Spore Wars: That's the movie take-off term Leonard Gianessi uses in discussing the very important role that fungicides play in U.S. and world crop production.
From strawberries to peanuts to pecans and a host of other crops in between, major increases in production have paralleled the development and adoption of effective fungicides, he says.
Gianessi, who heads the Crop Protection Research Institute, a non-advocacy research organization that focuses on the economic analysis of agricultural pests, pest management, and pesticide use/regulation, says U.S. producers — including organic growers — apply more than 100 million pounds of fungicides every year to battle fungi that could otherwise wreak havoc with crops.
“Thousands of different organisms release spores into the environment,” he said in outlining results of a CPRI study to members of the Southern Crop Production Association at their annual meeting at Orlando, Fla. “One tiny mushroom can release as many as 30 million spores. The prolific production of spores in the environment represents an immense potential threat to crops. Most acres of fruits and vegetables have fungi present and growers must deal with the problem each year.”
The study, which looked at 50 crops and 231 diseases that are controlled by fungicides, spanned the entire lower 48 states. Some of the findings:
83 percent of U.S. onions are sprayed with fungicides; in Georgia and Texas, growers can make as many as 10-11 applications. But the treatments result in a 30 percent production increase — 1.3 billion pounds of onions that could otherwise be lost to disease.
Scab, a perennial problem in southern pecan orchards, was treated for half a century with copper and lime. But when effective synthetic fungicides became available in the 1960s, yields that had been averaging only 8 pounds per tree jumped to 20-25 pounds per tree. Estimates are that without fungicides pecan growers would lose 53 million pounds yearly and $46 million in income.
Peanut producers suffered major losses from Rhizoctonia, “a truly awful disease,” and leaf spots until the advent of effective fungicides, which have resulted in yield increases as high as 2,000 pounds per acre.
Watermelon growers in the South were losing as much as 90 percent of their crop to bacterial fruit blotch, a disease that appeared in 1989 and spread throughout the region. With fungicides, losses now are minimal.
U.S. apple producers were suffering 25 percent to 50 percent losses from black rot and peach growers were losing as much as 75 percent of their crops to brown rot. Modern fungicides have cut those losses to 1 percent to 2 percent. In Georgia alone, peach growers got added production worth $35 million, a return of $17-$18 for every $1 spent on fungicides.
And though little mention is made of it, Gianessi says, fungicides are widely used by organic growers.
“Consumers assume sprays aren't used on organic farms, and the media have gone along with it. But the fact that these materials are being used by organic growers just emphasizes how important fungicide use is to crop production in this country.”